As known high strength metals such as zirconium and zirconium alloys, titanium and titanium alloys, alloyed steels and others become brittle when exposed to elementary hydrogen.
This embrittlement is known to be associated with the penetration of hydrogen atoms into the metal lattice and has been the subject of extensive research. In spite of the considerable efforts to understand and thus combat hydrogen embrittlement, this phenomenon is still a major cause of failure of vital equipment such as heat transfer piping in nuclear power plants made of zirconium alloys, supersonic aircraft segments made of titanium alloys and machine parts such as bolts and shafts made of alloyed steels.
Efforts have been made in the past to overcome this catastrophic phenomenon by two main methods. The first method is trying to block the ingress of hydrogen atoms into the metal by the use of coatings as diffusion barriers. The second method is by attempting to drive the hydrogen out from the metals by a subsequent heat treatment.
The first method has largely failed due to the extremely high permeability of hydrogen through most coating materials. Palladium coatings might be theoretically considered in view of its excellent properties and reasonable surface hardness, but commercially attractive processes for applying palladium films require high plating rates. But such plating rates often lead to undesirable film properties. In many such processes the palladium film is found to be brittle and susceptible to cracking.
The second method which requires a subsequent heat treatment is impractical for many parts which are too big to be introduced into a furnace, or are damaged by the heat treatment temperature.
It is an object of the present invention to provide a simple method for the treatment of high strength metals against hydrogen embrittlement. It is another object of the present invention to provide a simple method for the treatment of high strength metals against hydrogen embrittlement by an electro-chemical oxidation process. It is yet another object of the present invention to provide a simple method for the treatment of vital equipment made of a high strength metal against hydrogen embrittlement.